Here's an https link for anyone requiring that:
what ultimatum ?
The actual reality after this one was I believe ~1/3 of those remaining did not accept the ultimatum, but then Elon was very slow to follow up on actually terminating many of them, and later tried to negotiate some "essential" members back or threaten them with not giving the severance, so it's not clear how many actually left as a result of that.
[1] https://www.theverge.com/2022/11/17/23465274/hundreds-of-twi...